The more modern a garage door you have, the more safety features and options will be available to you. Garage doors in general are both vulnerable to penetration from the outside, and very dangerous in and of themselves. They are likely the largest moving part in your home and can pose a threat to small children, animals, and even adults.
Most new doors have an automatic reversal function- that is, when they detect something is in the path of the descending door, they immediately begin reversing such that the garage door doesn't crush whatever it is. They accomplish this by using either motion detectors or laser sensor 'eyes' that can sense an object that breaks their path to one another.
Many doors also come with an external keyless locking mechanism, which is great for convenience, but if anyone sees you putting your code in, can be hacked. It's probably a good idea to change your code up fairly frequently, especially if you noted anyone in your general vicinity while you were entering it.
The heyday of 'code grabber' technology is largely past- most garage door opener remotes now come with 'rolling code' technology such that their hailing frequencies can't be hacked. But it's always a good idea to flip the switches inside the remote and inside the opener to change them from their factory settings.